High-power thermionic tube



Dec. 3, 1929. J. BETHENOD HIGH POWER THERMIONIC TUBE Filed Dec. 28, 1925 a; heating provisions have been ments that are of advantage Patented Dec. 3, 19 29 UNITED .sr rcs PATENT orncs nm'nnnon, or rams, amen men-rowan THEBMIONIC roan Application filed December as, ieac,- Serial No. 688,101,

In my U. S. patent. application, Serial No. 642,946 for highpower electron generating device filed June 2, 1923, especially when the frequency of the in the cathode is relatively high, made so that the ma netic circuit may be incompletely closed. The object of the present application mainly is to outline and indicate certain arrangein this respect. As shown in the drawing herewith by way of example, cathode 2 has the form of a circular plate (disk) the cross section of which along a generatrix may, however, be made 16 of any desired cross-sectional shape at all.

, cientl 80 lik y This cathode is heated by the aid of the flux emanating from core' 5 excited by winding 6 through which is passed a current of suflihigh frequency. The grid which is ewlse of circular shape, is shown at 4.. The anode 3 finally is here supposed to be constituted by the bottom of a cylinder, and 1t forms jointly with a piece 1 made of a convenient insulating material (glass, quar z, etc.) an envelopeor bulb wherein a vacuum is established. It is to be noted that the joint between 1 and 3 is insured in a way as may be convenient to suppress all leakage. The

whole thus constructed could be disposed in 80 a vat 7 in which a chilling agent, such as oil,

etc., could be circulated. Such cooling could be confined, however, to anode 3, which in this glee must be constructed. with a double ttom.

At all events, the form and the constitution of the electrodes are arbitrary; in particular, anode 3 and cathode2 may be given, if so desired, either both or only one of them, the form of concave or convex mirrors, of cones or of truncated cones, etc., with this particular end in view of distributing as advantageously as feasible the electron emission from the cathode. It is furthermore nearly always of advantags to choose the thickness of cathode 2 and the frequency of the heating current in such a way that the alternating magnetic flux emanating from!) will not attain thegrid 4v and the anode 3, etc.

current producing the tube for and in lrance l'anuary 11, 1923.

the grid 4 is done away with,'one could utilize the flux passing through cathode 2 for the production in known manner a periodical interrupton of the current circulating between 3 and 2; a ring 8 built up of laminated sheets ofmagnetic material could then be 6 used to advantage for the pur ose of guiding the said flux. In'other wor s, the presence of ring 8 will attract or deflect the magnetic field emanating from core 5 for heating cathode 2 and thus prevent said magnetic field from reaching the grid and anode electrodes. However, this ring may be found useful under all circumstances and forms of arrangements. i

" Having described my invention, what I 7.

'a relatively large disk-like surface, means for heating said cathode by induction comrising a magnetic core and an induction coil or energizing said core, and a magnetic annular member for influencing the path of the flux emanating from said magnetic core.

2. In a high power thermionic tube, an anode and a cathode having disk-like surfaces disposed within an evacuated envelope for obtaining an increased electron emission therebetween, means for inductively heating said cathode including an inductance coil and a magnetic85 core disposed adjacent said cathode, and means separate from the electrodes of said preventing the flux emanating from said core from influencing the anode.

' JOSEPH BETHEN OD. 9o

Vat 7, moreover, made of redcopper, for

relatively large 

